[Qui-gon]

Everything runs through the ECU. The only switched input it has is on pin 26. The sequence is roughly as follows:

Turn key on this signals the ECU on pin 26 with 12v, supplies the starter button and the 2 relay coils under the seat (fan and fuel pump)with 12v.

On receipt of the on signal at pin 26 the ECU sends pin 19 to 0v thereby turning on the fuel pump relay. This switches on the pump, enables the lighting circuits and supplies power to the instrument panel. The pump runs for a few seconds then the ECU raises pin 19 to +12v thereby switching the relay off which in turn switches of lights feeds and the instrument panel.

The only things that bring the pump etc back on is either turning off the ignition switch and back on ( soft reset of the ECU) or as Bergerhag says, the pickup sensor being triggered by rotating the engine by kick or electric starter.

The output to trigger the coil is on pin 20 from memory. There should be a pulsed output on there when the engine is turning between 12v and 0v. 0v corresponds to "bang" time. The charging current for the coil is set internally by the ECU. This determines the width of the charging pulse. A scope or possibly analogue meter would show this.

If you need to go into it even deeper the chip inside the ECU that triggers the spark is a VBS025MSP by ST electronics. The data for it is easily found on the net.

Hope this helps